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is still the same； when my business is merely that of an observer and a traveller。 I know water from earth； land from sea； and mountains from vallies； because I have had experience of these objects； and confidently infer that； when certain appearances present themselves to my organs of sight； I shall find the same results to all my other senses； as I found when such appearances occurred to me before。
But the interval that divides the objects which occur upon and under the earth； and are accessible in all ways to our examination； on the one hand； and the lights which are suspended over our heads in the heavens on the other； is of the broadest and most memorable nature。 Human beings； in the infancy of the world； were contented reverently to behold these in their calmness and beauty； perhaps to worship them； and to remark the effects that they produced； or seemed to produce； upon man and the subjects of his industry。 But they did not aspire to measure their dimensions； to enquire into their internal frame； or to explain the uses； far removed from our sphere of existence； which they might be intended to serve。
It is however one of the effects of the improvement of our intellect； to enlarge our curiosity。 The daringness of human enterprise is one of the prime glories of our nature。 It is our boast that we undertake to 〃measure earth； weigh air； and state the tides。〃 And； when success crowns the boldness of our aspirations after what vulgar and timorous prudence had pronounced impossible； it is then chiefly that we are seen to participate of an essence divine。
What has not man effected by the boldness of his conceptions and the adventurousness of his spirit？ The achievements of human genius have appeared so incredible； till they were thoroughly examined； and slowly established their right to general acceptance； that the great heroes of intellect were universally regarded by their contemporaries as dealers in magic； and implements of the devil。 The inventor of the art of printing； that glorious instrument for advancing the march of human improvement； and the discoverer of the more questionable art of making gunpowder； alike suffered under this imputation。 We have rendered the seas and the winds instruments of our pleasure； 〃exhausted the old world； and then discovered a new one；〃 have drawn down lightning from heaven； and exhibited equal rights and independence to mankind。 Still however it is incumbent on us to be no less wary and suspicious than we are bold； and not to imagine； because we have done much； that we are therefore able to effect every thing。
As was stated in the commencement of this Essay； we know our own sensations； and we know little more。 Matter； whether in its primary or secondary qualities； is certainly not the sort of thing the vulgar imagine it to be。 The illustrious Berkeley has taught many to doubt of its existence altogether； and later theorists have gone farther than this； and endeavoured to shew； that each man； himself while he speaks on the subject； and you and I while we hear； have no conclusive evidence to convince us； that we may not； each of us； for aught we know； be the only thing that exists； an entire universe to ourselves。
We will not however follow these ingenious persons to the startling extreme to which their speculations would lead us。 But； without doing so； it will not misbecome us to be cautious； and to reflect what we do； before we take a leap into illimitable space。
SECTION II。
〃The sun；〃 we are told； 〃is a solid body； ninety…five millions of miles distant from the earth we inhabit； one million times larger in cubic measurement； and to such a degree impregnated with heat； that a comet； approaching to it within a certain distance； was by that approximation raised to a heat two thousand times greater than that of red…hot iron。〃
It will be acknowledged； that there is in this statement much to believe； and we shall not be exposed to reasonable blame； if we refuse to subscribe to it； till we have received irresistible evidence of its truth。
It has already been observed； that； for the greater part of what we imagine we know on the surface or in the bowels of the earth； we have； or may have if we please； the evidence of more than one of our senses； combining to lead to the same conclusion。 For the propositions of astronomy we have no sensible evidence； but that of sight； and an imperfect analogy； leading from those visible impressions which we can verify； to a reliance upon those which we cannot。
The first cardinal particular we meet with in the above statement concerning the sun； is the term； distance。 Now； all that； strictly speaking； we can affirm respecting the sun and other heavenly bodies； is that we have the same series of impressions respecting them； that we have respecting terrestrial objects near or remote； and that there is an imperfect analogy between the one case and the other。
Before we affirm any thing； as of our own knowledge and competence； respecting heavenly bodies which are said to be millions of millions of miles removed from us； it would not perhaps be amiss that we should possess ourselves of a certain degree of incontestible information； as to the things which exist on the earth we inhabit。 Among these； one of the subjects attended with a great degree of doubt and obscurity； is the height of the mountains with which the surface of the globe we inhabit is diversified。 It is affirmed in the received books of elementary geography； that the Andes are the highest mountains in the world。 Morse； in his American Gazetteer； third edition； printed at Boston in 1810＇46＇； says； 〃The height of Chimborazzo； the most elevated point of the vast chain of the Andes； is 20；280 feet above the level of the sea； which is 7102 feet higher than any other mountain in the known world：〃 thus making the elevation of the mountains of Thibet； or whatever other rising ground the compiler had in his thought； precisely 13；178 feet above the level of the sea； and no more。 This decision however has lately been contradicted。 Mr。 Hugh Murray； in an Account of Discoveries and Travels in Asia； published in 1820； has collated the reports of various recent travellers in central Asia； and he states the height of Chumularee； which he speaks of as the most elevated point of the mountains of Thibet； as nearly 30；000 feet above the level of the sea。
＇46＇ Article； Andes。
The elevation of mountains； till lately； was in no way attempted to be ascertained but by the use of the quadrant） and their height was so generally exaggerated； that Riccioli； one of the most eminent astronomers of the seventeenth century； gives it as his opinion that mountains； like the Caucasus； may have a perpendicular elevation of fifty Italian miles＇47＇。 Later observers have undertaken to correct the inaccuracy of these results through the application of the barometer； and thus； by informing themselves of the weight of the air at a certain elevation； proceeding to infer the height of the situation。
＇47＇ Rees； Encyclopedia； article； Mountains。
There are many circumstances； which are calculated to induce a circumspect enquirer to regard the affirmative positions of astronomy； as they are delivered by the most approved modern writers； with considerable diffidence。
They are founded； as has already been said； next to the evidence of our senses； upon the deductions of mathematical knowledge。
Mathematics are either pure or mixed。
Pure mathematics are concerned only with abstract propositions； and have nothing to do with the realities of nature。 There is no such thing in actual existence as a mathematical point； line or surface。 There is no such thing as a circle or square。 But that is of no consequence。 We can define them in words； and reason about them。 We can draw a diagram； and suppose that line to be straight which is not really straight； and that figure to be a circle which is not strictly a circle。 It is conceived therefore by the generality of observers； that mathematics is the science of certainty。
But this is not strictly the case。 Mathematics are like those abstract and imaginary existences about which they are conversant。 They may constitute in themselves； and i